Teletext is a means of sending text and simple geometric shapes to a properly equipped television screen by use of one of the "
vertical blanking interval" lines that together form the dark band dividing pictures horizontally on the television screen. Transmitting and displaying subtitles was relatively easy. It requires limited
bandwidth; at a rate of perhaps a few words per second. However, it was found that by combining even a slow data rate with a suitable memory, whole pages of information could be sent and stored on the TV for later recall. In the early 1970s, work was in progress in Britain to develop such a system. The goal was to provide UK rural homes with electronic hardware that could download pages of up-to-date news, reports, facts and figures targeting UK agriculture. The original idea was the brainchild of
Philips (CAL) Laboratories in 1970. In 1971, CAL engineer John Adams created a design and proposal for UK broadcasters. His configuration contained all the fundamental elements of classic teletext including pages of 24 rows with 40 characters each, page selection, sub-pages of information and vertical blanking interval data transmission. A major objective for Adams during the concept development stage was to make teletext affordable to the home user. In reality, there was no scope to make an economic teletext system with 1971 technology. However, as the low cost was essential to the project's long-term success, this obstacle had to be overcome. Meanwhile, the
General Post Office (GPO), whose telecommunications division later became
British Telecom, had been researching a similar concept since the late 1960s, known as
Viewdata. Unlike
Teledata, a one-way service carried in the existing TV signal,
Viewdata was a two-way system using telephones. Since the Post Office owned the telephones, this was considered to be an excellent way to drive more customers to use the phones. In 1972, the BBC demonstrated its system, now known as
Ceefax ("seeing facts", the departmental stationery used the "Cx" logo), on various news shows; this was not actual broadcast teletext but was transmitted using a wired connection. The
Independent Television Authority (ITA) announced its own service in 1973, known as
ORACLE (Optional Reception of Announcements by Coded Line Electronics). Not to be outdone, the GPO immediately announced a 1200/75 baud videotext service under the name
Prestel (this system was based on teletext protocols, but telephone-based). The TV-broadcast based systems were originally incompatible; Ceefax displayed pages of 24 lines with 32 characters each, while ORACLE offered pages of 22 lines with 40 characters each. In other ways the standards overlapped; for instance, both used 7-bit
ASCII characters and other basic details. In 1974, all the services agreed on a standard for displaying the information. The display would be a simple grid of text, with some
graphics characters for constructing simple graphics. The standard did not define the delivery system, so both
Viewdata-like and
Teledata-like services could at least share the TV-side hardware (which at that time was quite expensive).
Rollout in the United Kingdom The world's first demonstration of live broadcast teletext was a 50-page experimental transmission of ORACLE from the
Crystal Palace transmitter to an invited audience on 9 April 1973. The BBC began occasional test transmissions of Ceefax using dummy pages in 1973-4, and by June 1974 it had requested government authorisation to begin formal testing. Approval was granted and the BBC news department put together an editorial team of nine, led by editor Colin McIntyre, to develop a news and information service which began on 23 September 1974. Despite having been demonstrated first, ORACLE did not begin an experimental service until 30 June 1975. There was no industrial commitment to make consumer decoders until May 1975, when the UK arm of
Texas Instruments was announced as the first company to build decoders that would be sold to TV manufacturers for incorporation into their own sets by early 1976. By August 1977, it was estimated that up to 3000 teletext TVs had been sold, and both Ceefax and ORACLE were still officially considered "experimental" services. Neither service ever received a formal public launch to separate their experimental phase from full operation; the word "experimental" was simply dropped from references to them in the late 70s. From October 1977 to April 1978, an industrial dispute meant that ORACLE was blacked out nationally. From 1975 until 1977, ORACLE had operated for 12.5 hours a day Monday to Friday. A planned extension of its operating hours to cover the weekend prompted engineering staff at
LWT, the national origination point for ORACLE, to request more money for the additional duties; this was refused, which led to the affected staff refusing to maintain the equipment during the week. A test page was broadcast instead. By December 1979, it was estimated that there were about 14,000 teletext TVs in use, and that was the first year that the Queen's Christmas speech was publicly announced as being subtitled on Ceefax. The
"Broadcast Teletext Specification" was published in September 1976 jointly by the IBA, the BBC and the British Radio Equipment Manufacturers' Association. The new standard also made the term "teletext" generic, describing any such system. The standard was internationalised as
World System Teletext (WST) by
CCIR. Other systems entered commercial service, like
Prestel (in 1979). Teletext became popular in the United Kingdom when Ceefax, Oracle and the British government promoted teletext through a massive campaign in 1981. By 1982, there were two million such sets, and by the mid-1980s they were available as an option for almost every European TV set, typically by means of a plug-in circuit board. It took another decade before the decoders became a standard feature on almost all sets with a screen size above 15 inches (Teletext is still usually only an option for smaller "portable" sets). From the mid-1980s, both Ceefax and ORACLE were broadcasting several hundred pages on every channel, slowly changing them throughout the day. In 1986, WST was formalised as an international standard as CCIR Teletext System B. It was also adopted in many other European countries.
Development in other countries A number of similar teletext services were developed in other countries, some of which attempted to address the limitations of the initial British-developed system, by adding extended character sets or improving graphic abilities. For example, state-owned
RAI launched its teletext service, called
Televideo, in 1984, with support for
Latin character set.
Mediaset, the main commercial broadcaster, launched its
Mediavideo Teletext in 1993. La7Video in 2001, heir to TMCvideo, the teletext of TMC Telemontecarlo born in the mids 90s. Always in the 90s, Rete A and Rete Mia teletexts arrived. Retemia's teletext has not been functional since 2000, Rete A's since 2006, La7Video since 2014 and Mediavideo since 2022. These developments are covered by the different
World System Teletext Levels. In France, where the
SECAM standard is used in television broadcasting, a teletext system was developed in the late 1970s under the name
Antiope. It had a higher data rate and was capable of dynamic page sizes, allowing more sophisticated graphics. It was phased out in favour of
World System Teletext in 1991. In North America,
NABTS, the North American Broadcast Teletext Specification, was developed to encoding
NAPLPS teletext pages, as well as other types of digital data. NABTS was the standard used for both CBS's
ExtraVision and NBC's
NBC Teletext services in the mid-1980s. Japan developed its own
JTES In 1986, the four existing teletext systems were adopted into the international standard
CCIR 653 (now
ITU-R BT.653) as CCIR Teletext System A (Antiope), B (World System Teletext), C (NABTS) and D (JTES). The reason behind the replacement was that the original Cyclone system became harder to maintain over the years and the NOS even had to consult sometimes retired British teletext experts to deal with issues. For example, a recent issue was that a Windows update was incompatible with the old Cyclone system.
Decline The
World Wide Web began to take over some of the functions of teletext from the late 1990s. However, due to its broadcast nature, Teletext remained a reliable source of information during times of crisis, for example during the
September 11 attacks when webpages of major news sites became inaccessible because of the high demand. As the web matured, many broadcasters ceased broadcast of Teletext — CNN in 2006 and the BBC in 2012. In the UK the decline of Teletext was hastened by the introduction of
digital television, though an aspect of teletext continues in
closed captioning. In other countries the system is still widely used on standard-definition
DVB broadcasts. A number of broadcast authorities have ceased the transmission of teletext services. • International broadcasters: A live teletext is no longer available on
CNN International. Although many pages are still available, they have not been updated since 31 October 2006. •
United Kingdom: the founder of the world's first teletext service, the
BBC, closed its
Ceefax service in 2012 when Britain adopted a fully digital television broadcast system. The BBC maintains a
Red Button service on digital TV which includes access to the latest text news; that text news service is accessible on the BBC News Channel and during BBC One newscasts. Plans to shut it down in 2020 were changed and a reduced service is planned into 2021. Many channels on Sky still broadcast teletext subtitles and may still have a small number of active pages. Analogue teletext ended in each region after analog broadcasts finished: see
Digital switchover dates in the United Kingdom. •
Australia: the
Seven Network shut down the
Austext service on 30 September 2009. They said that the technology has come to the end of its useful service life and is not commercially viable to replace. •
New Zealand:
TVNZ Access Services announced the discontinuation of the service on April 2, 2013. A claim about equipment failures and that web sites have been used instead has been given as the reason. •
Ireland: In November 2019, it was announced that
RTÉ's
Aertel would be shut down as part of cost-cutting measures. On 2 October 2023, it was announced by RTÉ that the service would be shut down on 12 October 2023. •
Italy: Some nation-wide teletext services were switched off; for example,
MTV Video was active between 2000 and 2010, while "LA7 Video", the teletext service of
La7, was launched in 2001 but discontinued in 2014. •
Malaysia: RTM1 and 2 ceased transmission of teletext on 1 January 2000. Media Prima reduced the amount of content offered on the Infonet teletext service on TV 3 at the same time, and finally shut off the service for good on the first of January 2008. •
Singapore:
MediaCorp discontinued
its teletext service on 30 September 2013. Subtitling still continues to use teletext in Australia, New Zealand, and Singapore with some providers switching to using image-based DVB subtitling for HD broadcasts. New Zealand solely uses DVB subtitling on terrestrial transmissions despite teletext still being used on internal SDI links. == Technology ==